The present invention relates to a linear path slide with a slide which is arranged with a sliding guide slidingly movable in a housing and with a hydraulic driving gear which causes the movement of the slide and which has a piston arranged slidingly movable in a cylinder by constituting a hydraulic working space.
Linear path slides of the above mentioned type are used as actuators in different devices for the processing and machining of metallic materials and plastic or plastic composite materials. The functions of these structural components typically include the pressing, forming, stamping, bending, beading, punching, jointing, jointing pressing as well as the carrying out of feeding functions with special requirements. Particular requirements are made to the properties of linear path slides among which especially a high energy density, a very high guiding exactitude as well as a very high stiffness against transverse loads and torsion are to be found. Furthermore, they should be constructed as compact as possible and allow, as standardized basic structural components, a flexible universal range of application. Moreover, properties such as maintenance-freedom during the whole lifetime, a robust construction for the use in polluted environment, the possibility of any fitting position, absolute tightness (for example by overhead mounting) and not least a low-cost production are desirable.
Different configurations of linear path slides are known. Because of the required high energy density, they are preferably hydraulic devices. However, basically the design as a pneumatically driven device is also possible.
Especially combinations of customary linear cylinders are known as compact built-in modules which are formed with stiff linear guiding units by xe2x80x9csaddle-mountingxe2x80x9d or by constituting a constructional longitudinal combination.
From DE-GM 71 04 168, we know a hydraulically or pneumatically acting slide for translating or swivelling blades, flaps or containers for which the hydraulic working spaces are configured in the stemple of the device. In order to protect the piston rod of the device used in severe conditions against dirt, faling rocks and the like, it is surrounded by a protecting sheath. The slide is guided only by the piston rod and thus does not show any torsion stiffness. Therefore, it is appropriate only for receiving linear forces.
Moreover, hydraulic block cylinders are known, the housings of which have additional bore holes for guiding rods which are placed parallel to the actual hydraulic cylinder. The piston rod head and one to usually four guiding rods at the most are screwed to each other in a top plate resistant to bending. This arrangement guarantees flexural strength and torsional strength.
Furthermore, from DE 295 17 615 U1, we know a linear path slide with a slide, which is placed slidingly movable in a housing with guide rollers and resistant to torsion, and with a hydraulic driving gear which causes the displacing of the slide and which shows a piston placed slidingly movable in a cylinder by constituting a hydraulic working space. Due to the only point support of the slide valve on the rollers, the torsional strength and the capacity of absorbing transverse loads are however limited.
Moreover, the linear path slide shows a relatively big axial overall length.
Another configuration of a linear path slide (Manufacturer Heidel GmbH und Co, KG, Viersen, Germany) is known for the particularly high requirements in the field of cutting tools. This embodiment is characterized by a prismatical slide with an usually right-angled cross-section. The slide core is guided with a cast housing absolutely free from backlash and maintenance-free (for lifetime) due to a special heavy-load slideway technique. The slide shows a pocket into which a special hydraulic cylinder is inserted laterally to the movement axis. This hydraulic cylinder shows a piston with two continuous piston rods or with a piston rod and a driving slot which act onto the front sides of the pocket in the slide and thus transfer the forces of pressure onto the slide for a forward and a back motion. The hydraulic special cylinder is provided on one longitudinal side with a mounting flange by means of which it is screwed on the slide housing. For this purpose, the slide housing has an opening on its upper longitudinal side. The hydraulic oil connections are also on this mounting flange. There is a lateral connection as well as a connection orientated upwards with a corresponding guiding of the pipes in order to be adapted to different confined mounting conditions. The described linear path slide is characterized by its heavy-load capacity and the precise slideway of the prismatical slide. However, its useability is limited in some cases by its size and weight. Moreover, a repair of the linear path slide is relatively complicated.
The aim of the invention is to obtain, for a linear path slide of the above mentioned type, a compacter construction with a reduced volume and a reduced weight. Simultaneously, the linear path slide should be easier to repair and should be flexibler in its useability. Not least the manufacturing costs should also be reduced.
Accordingly, the linear path slide contains in a known way a slide which is arranged slidingly movable in a housing with a sliding guide as well as a hydraulic driving gear which causes the displacing of the slide and which has a piston arranged slidingly movable in a cylinder by constituting a hydraulic working space. Accordingly, this linear path slide is characterized in that the cylinder and the working space are configured in the slide and the piston is fixed with respect to the housing.
Here, by xe2x80x9ccylinderxe2x80x9d, we do not necessarily understand a cylinder in the mathematical sense, i.e. with a circular cross-section, but any working space limited by parallel walls in which a piston, the cross-section of which corresponds to the cross-section of the working space, can move parallel to the walls. Besides a mathematical cylindrical shape, the xe2x80x9ccylinderxe2x80x9d can also show in particular a cross-section in form of a regular polygon.
In the linear path slide according to the invention, the functions of the slide and of the hydraulic driving gear are combined in a structural component. This is possible since the hydraulic driving gear is integrated into the slide itself. Many advantages result from this measure. So, the giving up of two separated structural components (slide, hydraulic driving gear) allows a compacter thinner construction by saving construction volume. Components are additionally saved (for example housing with cylinder bore hole and mounting flange) and thus a high saving of costs and weight is achieved. The falling away of junctures in which for example the mechanical pressure force introduction takes place from the hydraulic driving gear to the slide, causes a further reduction of the production costs and avoids potential sources of errors.
Furthermore, for the linear path slide according to the invention, the arrangement of the slide and of the hydraulic driving gear can ensue with a high symmetry, the cylinder and the piston being placed on the center axle/axle of movement of the slide. Thus, there results a central and symmetrical force introduction which avoids the occuring of tilting moments. This causes a lower parasitic stress and increases the reliability and the longevity of the structural component. For linear path slides with a traditional construction, a corresponding symmetrical configuration would have resulted in considerably bigger structural shapes with an inacceptable specific power capacity.
Advantageous configurations of the invention are characterized in the subclaims.
The slide is constructed preferably as a prismatic slide. Thus, a high precision and a high stiffness are obtained in an experienced way.
Furthermore, it is preferred that the sliding guide, which is placed between the slide and the housing, is produced by a casting process. Such a casting process results on the one hand in a very high quality sliding guide and is simultaneously very advantageous as to the costs.
In an advantageous further development of the invention, the piston separates the cylinder into two separate working spaces, a volume increasing of the working spaces resulting in an opposite movement of the slide. In this way, it is possible through the inflow of hydraulic media and a pressure feeding into the corresponding working space to cause an active forward movement of the slide as well as an active back movement thereof. Since the piston divides the existing cylinder space into two parts, an optimal using of this space is simultaneously obtained.
For a possible realization of this alternative of the invention, the piston is placed at the end of a piston rod which has a smaller diameter than the piston and which is guided outwards on one side of the cylinder (i.e. of the slide). Here, the duct of the piston rod is tightly sealed all around so that no hydraulic media can flow out. In this arrangement, the piston separates the cylinder space into two working spaces which can be designated as lying on this side and on the other side of the piston rod. An introduction of pressure into the respective working spaces affects different sides of the piston and thus results in corresponding opposite forces onto the slide.
For fulfilling their function, the hydraulic working spaces must be provided with a feeding pipe for hydraulic media (for example oil). This feeding pipe is preferably placed in the piston and in the piston rod connected with the piston. Such an arrangement utilizes the fact that, on the one hand, the piston of the linear path slide according to the invention is fixed and, on the other hand, that it constitutes a part of the delimiting walls of the working space. Thus, the feeding pipe of the hydraulic media can be guided without problem from an outer connection through the piston rod and the piston to the place of use (and back). This is naturally also the case when, as in an above described embodiment of the invention, two working spaces are configured within the slide.
In the last mentioned case in which two different working spaces are fed with feeding pipes through the piston, these feeding pipes are preferably placed parallel or concentrically in the piston. Since the parallel arrangement allows a simpler fabrication due to deep bore holes with less structural components, the concentrical arrangement is especially chosen when the linear path slide should be configured very compact.
In a further development of the invention, the slide has a rear and/or a front limit stop sensor. This sensor allows to ascertain and to supervise if the slide is at one of the limit stops. This information is generally important for the higher processing step so that the precise detection of this state can advantageously be used for controlling the whole process.
The piston is detachably connected with the housing, whereby especially a screw-type and/or bayonet-type fixing is possible as a connection. A maintenance and repair of the linear path slide is possible by loosening the piston from the housing. Here, only one component has to be loosened in order to simultaneously obtain the access to the hydraulic space and to the slide. The maintenance of the linear path slide is thus considerably simplified which becomes apparent in the lower operating costs and in a longer lifetime.
In a further development of the invention, it is provided that the hydraulic cylinder is no longer directly formed by the inner wall of the stemple but by a separate cylinder case. This case is placed in a corresponding opening in the stemple. Such an arrangement has the advantage that the hydraulic unit is entirely placed in the cylinder bush and can also thus be entirely disassembled from the rear side of the linear slide without the slide itself having to be removed. Tools mounted on the slide such as, for example, precisely aligned cutters or the like have not to be removed. Thus, the risk of a deterioration of the inner wall or of the sliding guide by the tools is excluded. Moreover, the hydraulic oil is encapsulated by the cylinder bush and thus cannot soil the mounting place. Finally, the widening of the stemple is also avoided, since the hydraulic pressure does not act directly onto the stemple but onto the cylinder bush. This is extremely advantageous considering the anyway narrow tolerances of the slide gap.